Use of Phosphonylated Nitroxides and Alkoxyamines in Controlled/"Living" Radical Polymerization

Mercier, Christophe Le; Lutz, Jean‐François; Marque, Sylvain R. A.; Moigne, F. Le; Tordo, Paul; Lacroix‐Desmazes, Patrick; Boutevin, Bernard; Couturier, Jean‐Luc; Guerret, Olivier; Martschke, Rainer; Sobek, Jens; Fischer, Hanns

doi:10.1021/bk-2000-0768.ch008

Cited by 47 publications

(87 citation statements)

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“…DEPN was synthesized according to a procedure in the earlier literature. 15,37 Synthesis of Uracil-TEMPO Unimolecular Initiator. 6-Chloromethyluracil (1.69 g, 10.5 mmol), TEMPO (1.64 g, 10.4 mmol), and dNbpy (170 mg, 0.42 mmol) were dissolved in dimethyl sulfoxide (DMSO, 10 mL).…”

Section: Methodsmentioning

confidence: 99%

Synthesis of Chain End Functionalized Multiple Hydrogen Bonded Polystyrenes and Poly(alkyl acrylates) Using Controlled Radical Polymerization

2004

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Hydrogen bonding uracil functionalized polystyrenes and poly(alkyl acrylate)s were synthesized via stable free radical polymerization. Quantitative chain end functionalization was achieved using novel uracil containing TEMPO-and DEPN-based alkoxyamine unimolecular initiators. Polymerizations were conducted at 130°C and yielded functionalized homopolymers with narrow molecular weight distributions (M w/Mn ∼ 1.20) and predictable molecular weights. Polymerizations of both n-butyl acrylate and styrene using the DEPN-and TEMPO-based alkoxyamines resulted in molecular weight control over a wide range of conversions. Terminal functionalization of poly(alkyl acrylate)s with hydrogen bonding groups increased the melt viscosity at temperatures below 80°C, which was defined as the dissociation temperature, and as expected, the viscosity approached that of the nonfunctional analogues above this temperature. The hydrogen bonding effect was also evident in thermal (DSC) analysis and 1 H NMR spectroscopic investigations, and low molar mass polystyrenes exhibited glass transition temperatures that were consistent with a higher apparent molar mass. 1 H NMR spectroscopy confirmed the presence of a single hydrogen bonding group at the chain terminus, which was consistent with a well-defined initiation process for two families of novel alkoxyamines.

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Section: Methodsmentioning

confidence: 99%

Synthesis of Chain End Functionalized Multiple Hydrogen Bonded Polystyrenes and Poly(alkyl acrylates) Using Controlled Radical Polymerization

2004

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“…[24,25] We and others have shown that the C-ON bond in alkoxyamines is either strengthened by anomeric [26,27] (due to, for example, a heteroatom bound to the carbon) and polar effects [24,[27][28][29][30] [due to an electronwithdrawing group (EWG) bound to the nitrogen atom] or weakened by the steric strain and polar effects of both alkyl and nitroxyl fragments. [15,17,21,24,26,[31][32][33][34][35] Furthermore, stabilization [24,[26][27][28]31,33] of the released alkyl and nitroxyl radicals [27,29] − stabilized by an intramolecular hydrogen bond − also weakens the C-ON bond. A few years ago, studies [24] on TEMPO (2,2,6,6-tetramethylpiperidin-N-oxyl)-based alk-oxyamines showed that the presence of a methyl group on the carbon atom of the C-ON bond reduces the activation energy of homolysis by roughly 17 kJ/mol.…”

Section: Introductionmentioning

confidence: 99%

Alkoxyamine C–ON Bond Homolysis: Stereoelectronic Effects

Beaudoin¹,

Bertin²,

Gigmès³

et al. 2006

Eur J Org Chem

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Keywords: Alkoxyamines / Density functional calculations / Linear free energy relationships / Through-space interactions / Structure elucidation Alkoxyamines and persistent nitroxides are important regulators of nitroxide-mediated radical polymerization (NMP) reactions. Because polymerization times decrease with an increase in the rate constant for the homolysis of the C-ON bond between the polymer chain and the nitroxyl moiety, the factors influencing the cleavage rate constant are of considerable interest. Therefore, it was interesting to check whether the methyl effect (+17 kJ/mol for each methyl added onto the carbon atom of the C-ON bond) observed in the TEMPO-based alkoxyamine series was also observed in the SG1 [N-tert-butyl-N-(1-diethoxyphosphoryl-2,2-dimethylpropyl)aminoxyl] series. Moreover, we extended the incremental substituent scale proposed earlier and confirmed the

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“…The radical polymerization of acrylates did not fall under control with this alkoxyamine. The structure of the nitroxide is thus one of the key features for the success or failure of NMP [21]. Moreover, Catala et al recently developed new acyclic α-hydrogen containing nitroxides with a sulfoxide group in β-position (N-tert-butyl-(1-tert-butyl-2-ethylsulfinyl)propyl nitroxide or BESN) and the parent alkoxyamines [22][23].…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, Catala et al recently developed new acyclic α-hydrogen containing nitroxides with a sulfoxide group in β-position (N-tert-butyl-(1-tert-butyl-2-ethylsulfinyl)propyl nitroxide or BESN) and the parent alkoxyamines [22][23]. Control was imparted to the radical polymerization of styrene, ethyl and n-butylacrylate at quite low temperatures (100 and 90 °C, or below), which emphasizes again that the structure of the nitroxide has a decisive effect on the position of the equilibrium between the active and the dormant species [21], and thus on the control of the NMP process.…”

Section: Introductionmentioning

confidence: 99%

Ability of nitrones of various structures to control the radical polymerization of styrene mediated by in situ formed nitroxides

Sciannamea

Guerrero‐Sánchez

Schubert

et al. 2005

Polymer

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The ability of several nitrones to control the radical polymerization of styrene at 110 °C has been investigated by high-throughput experimentation. The nitrone/free radical initiator pair dictates the structure of the nitroxide and the alkoxyamine formed in situ, which determines the position of the equilibrium between the active and the dormant species operating in the nitroxide-mediated polymerization. For the styrene polymerization to be controlled, the nitrone must be reacted with 2,2′-azo-bis-isobutyronitrile (AIBN) at 85 °C, prior to addition of styrene and polymerization at 110 °C. The effect of the nitrone structure on the kinetics of the styrene polymerization has been emphasized. Amongst all the nitrones tested, those of the C-phenyl-N-tert-butylnitrone (PBN) type are the most efficient in terms of polymerization rate, control of molecular weight and polydispersity. Electrophilic substitution of the phenyl group of PBN by either an electrodonor or an electroacceptor group has only a minor effect on the polymerization kinetics. Importantly, the polymerization rate is not governed by the thermal polymerization of styrene but by the alkoxyamine formed in situ during the pre-reaction step. The initiation efficiency is, however, very low, consistent with a limited conversion of the nitrone into nitroxide and alkoxyamine.

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Use of Phosphonylated Nitroxides and Alkoxyamines in Controlled/"Living" Radical Polymerization

Cited by 47 publications

References 0 publications

Synthesis of Chain End Functionalized Multiple Hydrogen Bonded Polystyrenes and Poly(alkyl acrylates) Using Controlled Radical Polymerization

Synthesis of Chain End Functionalized Multiple Hydrogen Bonded Polystyrenes and Poly(alkyl acrylates) Using Controlled Radical Polymerization

Alkoxyamine C–ON Bond Homolysis: Stereoelectronic Effects

Ability of nitrones of various structures to control the radical polymerization of styrene mediated by in situ formed nitroxides

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